Okay,
I have an idea, if your willing to go through with this, ill do the math and post the numbers.
Hlx Stats tracks all of the weapon kills on a weekly basis. Since it is updated live that means that if you were to track the kills on a monthly basis. At the end of each week at say midnight someone could go on hlx stats and write down all the numbers. Then after another week, when the new numbers are collected, you write down the next set. Until after a total of 28 days. You can post the total numbers and list the winners. Then for the next 2-3 days you can have some bragging rights until the first of the new month. Thus restarting the entire cycle.
I think it would give the more hardcore players a chance to truly test their mettle. But like i said up there, i would be more than happy to do the work.
Plus on a side note, you could also track who has the most kills on a map over the month, and also see who gets the most kills overall.